Baylissite is a rare hydrated potassium magnesium carbonate mineral that typically forms as delicate, colorless to white prismatic crystals. It is most frequently found in complex alkaline rock environments or rare evaporite deposits where specific geothermal conditions facilitate its growth.
Is this baylissite?
5-step field checkRun through these checks against the specimen in your hand. The more boxes tick, the more confident the ID.
- 1Test the hardnessTry to scratch baylissite with a known reference. Baylissite sits at Mohs 2 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Baylissite leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Baylissite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: colorless, white.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: prismatic crystals, radial aggregates.
Often confused with
Baylissite vs. its common look-alikes — and how to tell them apart in the field.
Often found alongside baylissite
Minerals reported to co-occur with baylissite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- K₂Mg(CO₃)₂·4H₂O
- Mohs hardness
- 2
- Density
- 2.29 g/cm³
- Streak
- White
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Monoclinic
- Crystal habit
- Prismatic Crystals, Radial Aggregates
- Cleavage
- Perfect
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Alkaline Igneous Rocks, Evaporites
- Typical price
- $50-300 per specimen
Where rockhounds find baylissite
Classic worldwide localities
- Khibiny Massif, Russia
- Allchar, North Macedonia
- Poudrette quarry, Canada
Field-hunting tip
Look in alkaline igneous rocks, evaporites country — that is the host setting where baylissite typically forms. If you start seeing dawsonite, nahcolite, tychite in float, you are in the right ground. Field specimens usually show a prismatic crystals, radial aggregates habit, so train your eye for that shape before scanning the outcrop.





